adjectives, which are also known as compound adjectives, normally
use more and most for the comparative and superlative
forms. This is the general rule. Sometimes we have to use more/most
if, for example, the adjectival part of the compound ends in -ed.
So, sun-tanned would have to be more sun-tanned, just
as tanned would have to be more tanned:
Youre more sun-tanned than I am.
it is not so clear-cut, so we would say that one form is more likely
than the other. In your examples, Babek, both are quite possible,
it seems to me.
If you want to try some examples look at our Message
Board in the You, Me and Us part of our website.